It is known that glass bottles and/or vials for pharmaceutical use are produced from a glass tube, which is cut and modeled into the desired shape by means of a flame and then undergoes annealing treatment. The glass used can contain compounds, such as metal oxides, which in use can partly pass in solution into the pharmaceutical product contained in the bottle. Furthermore, due to surface tension phenomenon, it can be difficult to accurately extract the pharmaceutical product contained in the bottle or in the vial, for example by means of a syringe, due to the shape assumed by the meniscus of the liquid pharmaceutical product contained in the bottle/vial.
To avoid these drawbacks, the glass bottles and vials for pharmaceutical use are internally siliconed, i.e. their inner surface is coated at the end of the production phases with a fine layer of liquid silicone, subsequently baked to guarantee perfect adhesion to the walls of the bottle.
It is nevertheless extremely difficult in the known art to obtain a silicone coating layer of the inner wall of the glass bottles or vials for pharmaceutical use which is uniform and without creating undesired accumulations of silicone in one or more points of the bottle/vial which accumulations, in addition to constituting a waste of raw material, can create problems during filling and visual inspection at the manual or automatic optical bench and/or during use of the bottles/vials.